A tensile strength apparatus with the facility to monitor negative pore-water pressure

I. Murray, A. Tarantino, F. Francescon

Research output: Contribution to journalArticle

Abstract

This paper presents a new testing method for investigating the behaviour of clayey geomaterials subjected to a tensile (negative) total stress. The method includes the use of high capacity tensiometers to measure the pore-water pressure of the test specimen, an aspect which has not been demonstrated in any other direct tensile testing method. This addition allows interpretation of failure data in terms of effective stress rather than total stress, which is the approach that should be pursued in the saturated range. The test specimen shape and loading method have been modified from those commonly seen in existing literature to ensure that the direction of the major principal stress in the failure zone coincides with the direction of the externally applied tensile force, allowing for a more accurate analysis of tensile failure. Results are shown for saturated specimens and compared to results obtained for the same soil in uniaxial compression, using a modified version of the presented uniaxial tensile method, and a triaxial compression test. It is demonstrated that crack initiation occurs by shear failure if the data is interpreted in terms of effective stress rather than total stress, and that the failure mechanisms under tension do not differ from compression.
LanguageEnglish
Number of pages38
JournalGeotechnical Testing Journal
StateAccepted/In press - 22 Jun 2018

Fingerprint

tensile strength
porewater
Tensile strength
testing method
compression
effective stress
Water
tensiometer
failure mechanism
crack
Tensile testing
Crack initiation
Soils
method
test
soil
Testing

Keywords

  • clay
  • cracking
  • failure
  • high capacity tensiometer

Cite this

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title = "A tensile strength apparatus with the facility to monitor negative pore-water pressure",
abstract = "This paper presents a new testing method for investigating the behaviour of clayey geomaterials subjected to a tensile (negative) total stress. The method includes the use of high capacity tensiometers to measure the pore-water pressure of the test specimen, an aspect which has not been demonstrated in any other direct tensile testing method. This addition allows interpretation of failure data in terms of effective stress rather than total stress, which is the approach that should be pursued in the saturated range. The test specimen shape and loading method have been modified from those commonly seen in existing literature to ensure that the direction of the major principal stress in the failure zone coincides with the direction of the externally applied tensile force, allowing for a more accurate analysis of tensile failure. Results are shown for saturated specimens and compared to results obtained for the same soil in uniaxial compression, using a modified version of the presented uniaxial tensile method, and a triaxial compression test. It is demonstrated that crack initiation occurs by shear failure if the data is interpreted in terms of effective stress rather than total stress, and that the failure mechanisms under tension do not differ from compression.",
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A tensile strength apparatus with the facility to monitor negative pore-water pressure. / Murray, I.; Tarantino, A.; Francescon, F.

In: Geotechnical Testing Journal, 22.06.2018.

Research output: Contribution to journalArticle

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AU - Tarantino,A.

AU - Francescon,F.

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N2 - This paper presents a new testing method for investigating the behaviour of clayey geomaterials subjected to a tensile (negative) total stress. The method includes the use of high capacity tensiometers to measure the pore-water pressure of the test specimen, an aspect which has not been demonstrated in any other direct tensile testing method. This addition allows interpretation of failure data in terms of effective stress rather than total stress, which is the approach that should be pursued in the saturated range. The test specimen shape and loading method have been modified from those commonly seen in existing literature to ensure that the direction of the major principal stress in the failure zone coincides with the direction of the externally applied tensile force, allowing for a more accurate analysis of tensile failure. Results are shown for saturated specimens and compared to results obtained for the same soil in uniaxial compression, using a modified version of the presented uniaxial tensile method, and a triaxial compression test. It is demonstrated that crack initiation occurs by shear failure if the data is interpreted in terms of effective stress rather than total stress, and that the failure mechanisms under tension do not differ from compression.

AB - This paper presents a new testing method for investigating the behaviour of clayey geomaterials subjected to a tensile (negative) total stress. The method includes the use of high capacity tensiometers to measure the pore-water pressure of the test specimen, an aspect which has not been demonstrated in any other direct tensile testing method. This addition allows interpretation of failure data in terms of effective stress rather than total stress, which is the approach that should be pursued in the saturated range. The test specimen shape and loading method have been modified from those commonly seen in existing literature to ensure that the direction of the major principal stress in the failure zone coincides with the direction of the externally applied tensile force, allowing for a more accurate analysis of tensile failure. Results are shown for saturated specimens and compared to results obtained for the same soil in uniaxial compression, using a modified version of the presented uniaxial tensile method, and a triaxial compression test. It is demonstrated that crack initiation occurs by shear failure if the data is interpreted in terms of effective stress rather than total stress, and that the failure mechanisms under tension do not differ from compression.

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